Hot Birds Disperse More Non-Native Seeds
Deshpande, P., Johansson, N., Kluen, E., Lehikoinen, A., & Thorogood, R. (2024). Changing bird migration patterns have potential to enhance dispersal of alien plants from urban centres. Global Change Biology, 30(11), e17572. https://doi.org/10.1111/gcb.17572
Written by Alanna Richman, edited by Bethany Bradley
Summary
“Sleeper” species are non-native species that are established in an ecosystem but have not yet become invasive. Past analyses of sleeper species have focused on how changing climate could awaken some sleeper species (synthesis here). However, climate change could also affect how non-native species are dispersed into natural habitats, leading to faster conversion from established to invasive. Deshpande et al. (2024) highlight how climate-driven changes in bird migration favor the dispersal of non-native fruits and seeds from cities into more natural habitats.
In Helsinki, Finland, streetscapes are dominated by non-native, ornamental fruiting plants. These plants attract large quantities of frugivorous birds, which now overwinter or migrate later due to climate change. This extends the period in which these birds disperse the seeds of these non-native plants outside of cities. Despite the lower abundance of non-native plants when compared to native plants, the ease of availability has led to comparable dispersal of their seeds by frugivorous birds. Some of these non-native plant species have been observed in forest fragments near Helsinki, indicating that non-native seed dispersal via birds is already occurring. This paper emphasizes that birds could be dispersing non-native plant seeds out of urban and suburban landscaping more quickly than previously thought. They also illustrate how longer seasons provide more opportunities for seed dispersal by frugivorous birds.
Take Home Points
Urban streetscapes act as hotspots for seed dispersal processes due to their abundance of non-native fruit plants that attract frugivorous birds.
Climate change is altering the timing of frugivorous bird migration and overwintering, extending the amount of time these birds disperse seeds from urban landscapes into surrounding habitats.
Altered bird migration patterns in combination with urban planting choices can accelerate the transition of non-native plants in cities from “sleeper” species to invasive plants into natural landscapes.
Management Implications
Ornamental plants with the potential to become invasive may become invasive faster due to more opportunities for spread.
Management strategies that include Early Detection and Rapid Response (EDRR) are most effective for addressing risk from emerging invasive species.
Related papers
Frank & Just 2020, O’Uhuru et al. 2024, Sleeper Species Synthesis
Keywords
Invasive plants, phenology, frugivory, migratory birds, seed dispersal, urban ecology, climate change, sleeper species